Generally, three-dimensional photonic microstructures have been variously utilized in an imaging field, a display field, an illumination field, and the like. A micro prism, which is a kind of three-dimensional photonic microstructures, has been used in the imaging field, and an asymmetric micro lens or a micro slant mirror has been used in the display field in order to increase brightness of a reflective liquid crystal display (LCD). The three-dimensional photonic microstructures used in several fields as described above may substitute for a role of an existing photonic device, may implement a function that may not be implemented by the existing photonic device, and may become small and light. Therefore, several studies on a fabrication method of three-dimensional photonic microstructures have been currently conducted, and a fabrication method of three-dimensional photonic microstructures according to the related art has been disclosed in Korean Patent Laid-Open Publication No. 10-2009-0097858 (entitled “Method and Arrangement for Manufacturing Optical Products with Complex Three-Dimensional Forms” and published on Sep. 16, 2009).
As a typical fabrication method of three-dimensional photonic microstructures, there are a gray-scale lithography method, a direct laser writing method, a thermal reflow method, and the like.
As a method of fabricating three-dimensional photonic microstructures using a gray-scale lithography, there are mainly two methods. One is a method of using a high energy beam sensitive glass (HEBS glass), and the other is a method of using a chrome on glass (COG). In the case in which the HEBS glass is used as a mask, an electron beam (E-beam) writer is necessarily required in order to fabricate the mask. However, in the case in which the mask is fabricated using the electron beam writer, a cost required for fabricating the mask is increased. In addition, in the case in which the COG is used as a mask, a cost is low. However, a stepper for performing a projection lithography is required in order to fabricate photonic structures, such that a fabrication process of the photonic structures is complicated. In addition, since the fabricated structures have a step shape, it is not appropriate for being utilized in a high efficiency photonic device.
In the case in which the photonic device is fabricated using the direct laser writing method, it is not appropriate for a batch fabrication process of the photonic structures due to a scanning type.
The thermal reflow method has a disadvantage that shapes of fabricated photonic structures are restrictive.